New (2019): Our thermodynamic model now has a sensitivity analysis component that addresses the non-uniqueness of the apatite-melt-fluid system and can quantitatively match trends observed in different datasets. Manuscripts currently in preparation.
‘Volatiles’ are dissolved gases, an important component of most magmas. When magma ascends beneath a volcano, the dissolved gases form bubbles which expand and accelerate the magma upwards, fuelling explosive volcanic eruptions. Knowing the concentration of volatile elements in magmas stored underground, and whether there is a gas phase present, is important because it means we have a better chance of understanding how the volcano erupts. Apatite is a very common calcium phosphate mineral whose crystal structure contains volatiles including water and carbon dioxide and a range of trace elements. We are developing ways to use apatite to interpret volatile concentrations in magmas before eruption, and to ‘fingerprint’ the deposits of explosive eruptions. This will help us to understand why volcanoes erupt in the way they do, and will also help in studies of the ancient environment that rely on volcanic ash markers for chronology.
1. Stock, M.J., Humphreys, M.C.S., Smith, V.C., Isaia, R., Brooker, R.A. & Pyle, D.M. (2018) Tracking volatile behaviour in sub-volcanic plumbing systems using apatite and glass: Insights into pre-eruptive processes at Campi Flegrei, Italy. Journal of Petrology 59, 2463-2492
2. Riker, J.M., Humphreys, M.C.S., Brooker, R.A., de Hoog, C.J. & EIMF. (2018) First measurements of OH-C exchange and T-dependent partitioning of OH and halogens in the system apatite – silicate melt. American Mineralogist 103, 260-270
3. Stock, M.J., Humphreys, M.C.S., Smith, V.C., Isaia, R. & Pyle, D. (2016) Late-stage volatile saturation as a potential trigger for explosive volcanic eruptions. Nature Geoscience 9, 249-255
4. Stock, M.J., Humphreys, M.C.S., Smith, V.C., Johnson, R.D. & Pyle, D.M. (2015). New constraints on electron-beam induced halogen migration in apatite. American Mineralogist 100, 281-293
Apatite for eruption?
New ways to understand volcanic gas and trace explosive eruptions
University of Durham
University of Bristol
University of Oxford
University of Durham/ Bristol
University of Oxford
(PhD student)
Dr Roberto Isaia, INGV Naples, Italy
Dr Cees-Jan de Hoog, Edinburgh Ion Microprobe Facility, UK
Dr Michael Marks, University of Tuebingen, Germany
Dr Chris Tacker, North Carolina Museum of Natural Sciences, USA
Part of the city of Naples, looking across the crater formed by a huge eruption from Campi Flegrei volcano around 15,000 years ago. The cliffs on the skyline are the far side of the crater; the mass of housing in the foreground lies inside the crater.